Luggages or suitcases are often used for carrying personal items or articles, and for protecting the personal items or articles from damage when subjected to an external impact force. Therefore, a conventional luggage typically includes an integrally-formed hard shell that constitutes a body of the conventional luggage. However, the conventional luggage has a fixed volume and normally occupies a considerable amount of space, which is inconvenient when it comes to storage or transport of the conventional luggage.
To resolve this issue, collapsible luggages with adjustable volume size are designed, such as those disclosed in U.S. Patent Publication No. 20050016310, and U.S. Pat. Nos. 6604617B2 and 7849984B2. A conventional collapsible luggage typically includes a bottom part which is collapsible such that a distance between opposite front and rear parts of the conventional collapsible luggage is adjustable, and a volume of the conventional collapsible luggage can be reduced. However, since the bottom part of the conventional collapsible luggage is adapted to bear weight of the personal items or articles received in the conventional collapsible luggage, and is adapted for a plurality of wheels or a standing frame to be mounted thereon, the configuration of the bottom part being collapsible adversely affects the structural strength of the conventional collapsible luggage. Furthermore, since the rear part of the conventional collapsible luggage is typically mounted with a telescopic rod and is thus uncollapsible, and since an area of the rear part is typically larger than that of the bottom part, the conventional collapsible luggage still occupies a considerable amount of space even when the bottom part is collapsed.